This invention relates to a fluid level indicator for a reservoir wherein a signal is generated when the fluid level reaches a predetermined minimum level. More particularly, the invention covers a reservoir wherein a magnet is movable in response to the fluid level to actuate a reed switch.
A master cylinder in a vehicle brake system is provided with a reservoir to carry brake fluid. Throughout the life of the brake system increasing amounts of brake fluid are communicated from the reservoir to the master cylinder to accommodate lining wear and the associated piston adjustment. If the fluid level approaches a minimum level, it is desirable to provide a warning for a vehicle operator so that brake fluid can be added to the reservoir and the brake system checked for leaks or excessive friction lining wear.
Various fluid level indicators have been provided. Examples of these indicators can be found in U.S. Pat. Nos. 4,057,700 (Nakashima), 4,046,977 (Cadeddu), and 3,678,490 (Putt). In all of these examples, the indicators take up the entire height of the reservoir as a magnet is moved adjacent a reed switch to actuate a warning circuit. Where a float is provided, the float material is a plastic "foam", such as a porous resin or a two-part assembly requiring attachment before use with the master cylinder reservoir.
The present invention provides a fluid level indicator for a reservoir containing fluid, the indicator including a magnet which cooperates with a reed switch or the like to generate a signal when the fluid level in the reservoir is below a predetermined level and a carrier assembly engageable with the magnet to control movement of the latter, characterized in that said carrier assembly comprises a first part supporting said magnet thereto and a second part movable in response to the level of fluid in the reservoir to move said magnet from a rest position to an actuated position, said second part defining a weight which is greater than a weight for said first part and said magnet when said carrier assembly is out of the fluid, said first part and said magnet combined weight being greater than said second part weight when said carrier assembly is in the fluid, and said carrier assembly comprising a solid plastic-like material having a density which is less dense than the density of said magnet whereby said second part will move said first part as the fluid level approaches or reaches the predetermined setting.
It is an advantage of the present invention that the carrier assembly can be molded as a solid from a variety of plastic-like materials, thereby decreasing production time. It is also an advantage that the carrier assembly is disposed adjacent a base for the reservoir at all times to define a low profile for compact disposition within the reservoir.